Richard Berthelsen, general counsel of the NFL Players Association and a key figure in the football world for nearly four decades, told union staff Thursday that he will retire this spring.

Berthelsen, 67, joined the NFLPA in 1972 and has played an integral role in the sport’s labor battles and the growth of the players association and professional football. He also served as the union's interim executive director for seven months after the death of Gene Upshaw in 2008.

Player representatives and NFLPA staff learned of Berthelsen's decision today during the annual players' representatives meeting in Florida.

Berthelsen played a largely behind-the-scenes role at the union through the 1982 players' strike, but gained an increasingly prominent role with each passing controversy. He served as a top lieutenant to former executive directors Edward Garvey, Gene Upshaw, (who assumed the position in 1983) and DeMaurice Smith, the union chief since March 2009 who was unanimously re-elected earlier Thursday morning.

Berthelsen played a crucia role at the negotiating table during the 1987 strike, the 1993 collective bargaining and subsequent extensions and the 2011 lockout. He is expected to continue serving as union general counsel through mid-May, when his retirement will become official.